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Flashcards in Water Balance Deck (69):
0

Dehydration is a deficit in body fluids caused by what 6 things?

Vomiting, diarrhoea, excessive sweating, low water intake, drainage from burns, damage to thirst mechanism

1

What are the 9 things that are important about water in the body?

Universal solvent, chemical reactions occur in water, found as major component of plasma and cells, lubricant of joints and organs.highh ability to absorb and retain heat - stays in liquid state over broad range of temperature 0-100 degrees, large amount of heat required to increase its temperature - stabilises body temperature, sweating carries a lot of heat away from the body.

2

How many litres is our total body water?

32-40 L

3

How do we get water into the body?

Drinks (1500ml) food (750ml) water of metabolism (250ml)

4

How do we get rid of water from the body?

Urine (1500ml) stools (100ml) sweats (200ml) respiratory loss (700ml)

5

What is the body composition of an average 70kg man?

Water 60%
Fat 18%
Protein 16%
Carbohydrates 0.7%
Minerals 5.2%

6

Where is the water in the human body?

25L intracellular fluid, 12L extracellular fluid, 3L plasma

7

What is simple diffusion?

Movement from an area of high concentration to an area of low concentration through a semi - permeable membrane

8

What allows substances to move in and out of cells

Diffusion

9

How does an increase in temperature affect the rate of diffusion?

Increase motion of particles

10

How does molecular weight affect the rate of diffusion?

Larger molecules move slower

11

How does steepness of concentration gradient affect rate of diffusion?

Increased difference means increased rate

12

How does membrane surface area affect rate of diffusion?

Increase in area means increase in rate

13

How does membrane permeability affect rate of diffusion?

Increase in permeability means increase in rate

14

What is osmosis?

The diffusion of water from a lower to a higher concentration

15

Define a solution

A homogenous mixture of one or more dissimilar substances usually a liquid (solvent) and a solute (electrolyte - dissolved particle)

16

Name 3 types of solution that are based on size

Aqueous
Colloids
Suspensions

17

Aqueous solutions are made up of?

Small molecules which dissolve
Ionic compounds which dissociate
Electrolytes are soluble inorganic molecules whose ions conduct electricity in solution

18

Colloids are made up of

Proteins or other large molecules as solute

19

Suspensions are made up of

Even larger molecules than colloid solutions
Particles settle if undisturbed

20

What is the osmotic pressure?

The force (thrust) of water movement into the higher concentration solution

21

What and concentration solutions be measured as?

G/L - weight or volume
%
1 mole = number of atoms/molecules present in a sample equal to the molecular weight in grams

22

What is osmolarity?

Number of osmoles/L solution

23

The osmotic concentration of the body fluids have a great effect on what?

Cell function

24

The effect of osmolarity is dependant on what rather than what?

Number of particles dissolved rather than the weigh of the molecule

25

Osmotic concentration is expressed in what?

Osmoles/L or Kg

26

Osmolality is

Number if osmoles/kg of H20

27

Osmolarity is

Number of osmoles/L of H20

28

Name the 3 tonicity's that a cell can be

Isotonic
Hypotonic
Hypertonic

29

If a cell is in an isotonic solution

Concentration of electrolytes outside the cell is equal to that inside the cell
No water movement
No change in cell shape

30

A cell in a hypotonic solution

Has low concentration of salutes that do not cross the membrane, high water content
Dilute
Cells absorb water and swell, if solution is to dilute cell may burst (lysis)

31

Cell in a hypertonic solution

Low water concentration and high concentration of salutes that do not cross the membrane
Water moves to try and balance water/ion concentration
Cells in this solution would lose water and shrivel up

32

What happens when body water is low?

Baroreceptors and osmoreceptors send messages to the thirst centre in the hypothalamus. This releases ADH, we get thirst and a dry mouth and so drink

33

List 4 treatments for dehydration

Fluid therapy
Gelofusine
5% glucose solution
0.9% saline

34

What can over hydration cause?

Hyponatraemia
Water intoxication

35

Any fluid movement results in what?

Change in osmotic pressure, electrolytes on one side of the membrane therefore cell will change size

36

Water will always follow what?

Salts

37

What do we call substances that are dissolved in solutions?

Solutes

38

Which of the following is he most concentrated solution?
A - 0.9% saline
B - 100g/L saline
C - 9mg/100mls saline

B = 10%


C = 0.009%

39

What are the 5 functions of water in the body

Universal solvent
Chemical reactions occur in water
Major component of plasma and cells
Lubricant of joints and organs
Helps control body temperature

40

What is fluid intake and output controlled by?

Kidneys, anti diuretic hormone

41

Describe the process of water balance and ADH

Sensory nerve cells in the hypothalamus detect changes in the osmotic pressure of the blood. Nerve impulses from the osmoreceptors stimulate the posterior pituitary to release ADH. Raised osmotic pressure =blood more concentrated, ADH output is increased, increasing water reabsorption in the kidneys - negative feedback mechanism.

42

Define osmotic pressure

Force of water movement into the higher concentration solution.

43

What does extra cellular fluid In the interstitial spaces mainly consist of?

Blood, plasma, lymph and CSF fluid.

44

What is the role of extra cellular fluid?

Mainly lubrication

45

Give 3 examples of extracellular fluid

Synovial fluid, pericardial fluid (around the heart), pleural fluid (around the lungs)

46

What does interstitial fluid do?

Bathes all the cells of the body except the outer layers of the skin, medium through which substances pass from blood to body cells and vice versa.

47

What would a fall in blood potassium cause?

Muscle weakness and cardia arrhythmia

48

Name a difference between intracellular and extracellular fluid.

Intracellular fluid has a lot less sodium

49

What substances are found inside the cell in higher amounts?

ATP, protein and potassium

50

Define solute

Substances that are dissolved in solutions

51

Define solution

Mixture of 2 or more dissimilar substances, usually a liquid into which a solid is dissolved

52

Define osmoality

Osmotic pressure of substance expressed as osmoles of substance per kg of water

53

Define osmorality

Osmotic pressure of a substance expressed in terms of osmoles of substance per L of water

54

Define tonicity

Ability of a solution to affect the cell

55

Define electrolyte

A charged molecule, eg calcium, sodium, potassium

56

What is calcium involved in

Bones, muscle contractions, nerve excitability

57

What is sodium involved in

Action potential, osmotic pressure, nerve conduction

58

What is potassium involved in

Nerve cell returning to resting state

59

What is hydrogen involved in

Acid balance

60

What is chloride involved in

Transported with sodium and potassium

61

What is bicarbonate involved in

Acid balance - counter acts hydrogen

62

Give 2 examples of passive transport

Diffusion
Facilitated diffusion

63

What does active transport require

Energy

64

The transfer of what would require active transport?

Sodium, chloride, glucose

65

Which for, of transport moves up the concentration gradient and requires energy?

Active transport

66

What happens during facilitated diffusion?

Molecules are too big to diffuse across the membrane, bind to receptors in carrier proteins which causes molecule to change shape, molecule drops off carrier protein and ends up inside the cell,

67

Carrier proteins are always....

Molecule specific

68

Describe bulk transport

Form of active transport, particles that are too big, cell engulfs particle, forms vacuole, enzymes attach digest and spit out waste.